We studied patients with hypertension, angina pectoris, but with normal coronary angiograms. We hypothesized that these patients have an abnormality of their coronary vasculature which parallels the abnormality in the systemic vasculature causing hypertension, and that this abnormal coronary vasoconstriction results in myocardial ischemia. To prevent the confounding influences of coronary artery disease or left ventricular hypertrophy on estimates of coronary blood flow, patients with angiographic evidence of epicardial coronary artery disease or echocardiographic evidence of left ventricular hypertrophy were excluded. We studied the coronary blood flow in these patients in response to rapid atrial pacing and to intravenous ergonovine. We found that the patients who had reproducible chest pain during atrial pacing had a limitation in their coronary flow reserve. That is their maximal coronary blood flow was 30% less than compared to patients who did not have chest pain during rapid atrial pacing. In addition, it appeared that ergonovine caused further vasoconstriction resulting in decreased coronary blood flow in patients who had chest pain during atrial pacing. Therefore, it appears that patients who have hypertension and angina in normal coronary angiograms, but do not have left ventricular hypertrophy, have and abnormality of the coronary vascular reserve which appears to be a dynamic abnormality. This is the first study which shows an abnormality in coronary vasodilator reserve in hypertensive patients left ventricular hypertrophy.